| Fish soup is welcomed by consumers for the high nutrition, delicious taste and milkywhite sauce. Currently, products of fish soup on the market are mainly in the form of liquid.And some problems exist in the industrial processing of fish soup, such as low utilization rateof raw materials, high transportation cost, short shelf life, lack of portability and so on.Further, the market of instant fish soup is staying in the fast growing stage, showing a greatmarket potential. Consequently, cooking process, sterilization and drying process of instantfish soup were studied in this thesis, in aiming to provide the possibility of producingcondensed fish soup and fish soup powder with higher portability, longer shelf life and highercompetitiveness, by comparing to same products in the market. This writing also created ahigh practical application value for the further research of promoting deep processing of freshwater fish in large quantity and increasing the added value for fish products development.The effect of deodorization treatment and frying treatment on sensory quality of fishsoup were studied. The results showed that: The results showed that the pretreatment of rawmaterial, where fish pieces was soaked in deodorization liquid added1%yeast for1.0h,could effectively deodorize raw fish meat. The sensory quality of fish soup cooked by fishmeat with the treatment of frying for25-30s at170-190oC got dramatically higher scoresthan the one without the frying process, and its taste was close to home made fish soup.In order to optimize the boiling process, amino nitrogen, collagen and crude protein wereused as indicators to evaluate the effects of boiling process on the nutritional flavor and solidscontent of fish soup,and the composition of the fish soup and fish residue protein wereanalyzed with SDS-PAGE. Further, the multi-stage of boiling process and colloid millgrinding process were preliminarily investigated. The results showed that after fish piecesboiled for more than2.5h, most of the water-soluble protein and part of the salt solubleprotein in the fish pieces dissolve out，and the dissolution of collagen and amino nitrogenachieved balance; When the mass ratio of fish to water was between3.5:1-4.0:1and theboiling time reached2.5h, the solids concentration and total solids content in fish soup wererelatively appropriate; Using colloid mill to process fish soup residue as alternative totraditional multi-stage boiling process can effectively improve the utilization of raw materials.The effect of solids content on the stability of condensed soup was studied, and the beststerilization combinations of time and temperature were determined by measuring the heattransfer curve of product in sterilization process. The results showed that the condensed soupwith50%solids content is stable after sterilization process at121oC/(5.5-5-5.5)min, the Fvalue was about7.8, and inflation bags did not been found in constant temperatureexperimental, where the results proved the products meet the preservation requirements.Finally, sensory quality of the product got the highest scores.Eeffects of different drying methods and conditions on the quality of fish soup wereinvestigated to optimize the drying process, and the shelf life of fish soup powder was futherdetermined by the experiment of changing acid value and peroxide value of fish soup powderduring the storage. The results showed that the soup with higher concentration should not be used to freeze-drying process. And optimum conditions of spray drying were: the feedconcentration was20%-25%, inlet air temperature was170-180oC and the feed speed was25-30mL/min, the granular made from the mixture of soup powder and seasoning could getgood instantly solubility. Also, using the acid value of fat deterioration assessment indicatorsto predict the shelf life at normal temperature, the product could be stored for121days.The qualities of concentrated fish soup and fish soup powder were analyzed through thedetermination of product components, the total amino acid and free amino acid composition,GMP and IMP content, volatile flavor components and sensory evaluation. The resultsshowed that: fish soup powder and condensed soup were rich of nutrition, the amino acidcompositions of rehydration soup from fish soup powder and condensed soup were similar tothat of fresh soup, the glycine and histidine were the main flavor amino acid in the three kindsof fish soup by the analysis of free amino acid composition, the total content of umami aminoacid in the three kinds of fish soup were also similar. All of these revealed two products areable to keep the nutrition and flavor, where it similar to fresh fish soup. IMP content washigher than GMP, and nucleotide declined in varying degrees in three kind of fish soup; Theflavor substances from fresh fish soup were mainly made of aldehydes, alcohols, ketonescompound. Furan and pyridine appears in volatile flavor compound of fish soup fromcondensed soup, and volatile flavor compounds from soup powder mainly composed ofhydrocarbons, aldehydes, lipid and alcohols compounds, which mainly show fat sweet flavors;No significant difference in overall score of sensory evaluation of three kinds of soup. |
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